News feature: Not ending up like Scott

Satellites help map hidden crevasses in Antarctica

When great Antarctic explorers like Robert Falcon Scott made their way to the South Pole they were not only making history but also charting safe routes through which others could make the same journey.

Because of the difficulty and danger involved in surveying new routes in the Antarctic many of those same routes are still used today, but new work by Ohio State University researchers may be about to change that.

Aided by satellite surveys, computer image analysis software and a grant from the National Science Foundation, Carolyn Merry, a professor of civil engineering at Ohio State, has mapped new routes across the Ross Ice Shelf that promise to make travelling across this part of the Antarctic safer.

Ground travel across the ice shelf can be a treacherous business. Deep crevasses can get covered with snow, making them virtually invisible on the ground and spelling disaster for any vehicle that tries to travel over them. That danger was underscored in 1991 when a snow tractor fell into a crevasse.

Merry used images from the Landsat and SPOT satellites as the basis for her work and ran them through the Imagine mapping and visualisation software from Leica Imaging's Erdas subsidiary to enhance the images. Then, working with a colleague, she analyed the images for evidence of crevasses, which appeared as white lines.

Once her work was completed and a preliminary route had been mapped, a team from the US Army Corps of Engineers' Cold Regions Research and Engineering Laboratory and Antarctic Support Associates went onto the ice to do a more detailed survey. Using ground-penetrating radar the team was able to find hidden or buried crevasses that the satellite images had not picked up.

"With the ice-penetrating radar the team could map buried crevasses that we did not see with the Landsat and SPOT imagery," Merry. "We are only seeing the surface expression with these visible, shorter, wavelengths. The radar is a longer-wavelength sensor and can penetrate the ice surface."

The result was a route from McMurdo Station, on the Pacific side of the continent nearest to New Zealand, towards the Leverett Glacier in the Transantarctic mountains and then across the ice shelf to the South Pole. The route would take about two weeks to travel, Merry estimated.

While the original objective of the survey was to find safer travel routes that would make ground transport a viable alternative to air travel, a National Science Foundation cost analysis found air transport remains the cheaper option. That doesn't mean the work was a waste of time, said Merry.

"We learned much more about the flow patterns around McMurdo Station and this leads to more accurate maps of ice flow. We also came up with a better understanding of the ice mechanics of the ice shelf in this area."